The Devils will open the season without their No. 1 center, Travis Zajac, who will be out until mid-November following Achilles tendon repair Thursday.

“There’s no panic. That’s what we have depth for, and a minor-league system,” GM Lou Lamoriello said.

“It had to be repaired, so it was torn,” said Lamoriello, who said he did not know whether the vital tendon in his left calf was severed.

Lamoriello said Zajac suffered the injury during off-ice training that involved jumping. It is expected to require three months’ recovery.

“It’s a simple procedure, but it’s three months,” Lamoriello said. “He’ll be back sooner than you think.”

Zajac finished third in Devils scoring last season at 13-31-44, playing all 82 games. The 26-year-old, who will be late starting his sixth NHL season, stands 89-160-249 in 408 NHL games. He was the Devils’ first pick, 20th overall, in 2004.